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FormalConjectures.ErdosProblems.«749»

Erdős Problem 749 #

Reference: erdosproblems.com/749

theorem Erdos749.erdos_749 :
(∀ ε > 0, ∃ (A : Set ), 1 - ε (A + A).lowerDensity (Nat.cast AdditiveCombinatorics.sumRep A) fun (n : ) => 1) sorry

Let $\epsilon>0$. Does there exist $A\subseteq \mathbb{N}$ such that the lower density of $A+A$ is at least $1-\epsilon$ and yet $1_A\ast 1_A(n) \ll_\epsilon 1$ for all $n$?